Jonathan Steven Alexander

Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, United States

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Publications (4)9.9 Total impact

  • Jonathan Steven Alexander, Yuping Wang
    Hypertension Research 07/2012; 35(9):892-3. · 2.79 Impact Factor
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    ABSTRACT: Cytokines contribute to cerebro-vascular inflammatory and immune responses by inducing ECAMs' expression. Ischemic insults can be separated into aglycemic and hypoxic components. However, whether aglycemia, hypoxia or OGD plays a major role in dysregulating BBB or promotes immune cell infiltration via ECAMs' expression is not clear. We investigated how expression of ICAM-1, VCAM-1, MAdCAM-1, PECAM-1, E- and P-selectin in response to TNF-α, IL-1β and IFN-γ was altered by aglycemia (A), hypoxia (H) or combined oxygen glucose deprivation (OGD). A cell surface enzyme linked immunoabsorbent assay (cell surface ELISA) was used to analyze ECAM expression. We observed that ICAM-1 and PECAM-1 expressions were insensitive to hypoxia, aglycemia or OGD. Conversely, VCAM-1 and E-selectin were increased by hypoxia, but not by aglycemia. MAdCAM-1 and P-selectin were induced by hypoxia, and decreased by aglycemia. Patterns of cytokine-regulated ECAMs' expression were also modified by metabolic conditions. Our results indicate that patterns of inflammation-associated ECAMs represent cumulative influences from metabolic stressors, as well as cytokine activation. The expression of ECAMs following tissue injury reflects mechanistic interactions between metabolic disturbances, and alterations in tissue cytokines. Normalization of tissue metabolism, as well as cytokine profiles, may provide important targets for therapeutic treatment of inflammation.
    Microcirculation (New York, N.Y.: 1994) 02/2012; 19(2):155-65. · 2.37 Impact Factor
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    ABSTRACT: Infiltration of leukocytes into post-ischemic cerebrum is a well-described phenomenon in stroke injury. Because CD-8(+) T-lymphocytes secrete cytotoxic proteases, including granzyme-b (Gra-b) that exacerbates post-ischemic brain damage, we investigated roles of Gra-b in human stroke. To study the role of Gra-b in stroke, ischemic and non-ischemic tissues (from post-mortem stroke patients) were analyzed using immunoblotting, co-immunoprecipitation, terminal deoxy uridine nick end labeling (TUNEL) and Annexin-V immunostaining, and in vitro neuron survival assays. Activated CG-SH cells and supernatants were used to model leukocyte-dependent injury. Non-ischemic brain tissues were used as non-pathological controls. Non-activated CG-SH cells and supernatants were used as controls for in vitro experiments. Human stroke (ischemic) samples contained significantly higher levels of Gra-b and interferon-gamma inducible protein-10 (IP-10/CXCL10) than non-ischemic controls. In stroke, poly (ADP-ribose) polymerase-1 and heat shock protein-70 were cleaved to canonical proteolytic "signature" fragments by Gra-b. Gra-b was also found to bind to Bid and caspase-3. Gra-b also co-localized with Annexin-V(+) /TUNEL(+) in degenerating neurons. Importantly, Gra-b inhibition protected both normal and ischemia-reperfused neurons against in vitro neurotoxicity mediated by activated CG-SH cells and supernatants. These results suggest that increased leukocyte infiltration and elevated Gra-b levels in the post-stroke brain can induce contact-dependent and independent post-ischemic neuronal death to aggravate stroke injury.
    Brain Pathology 01/2011; 21(1):16-30. · 4.74 Impact Factor
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    The Open Gastroenterology Journal. 01/2008; 2(1):1-8.